NAAG Peptidase Inhibitors for the Treatment of Traumatic Brain Injury

描述(申请人提供)：创伤性脑损伤(TBI)是一个严重的公共卫生问题。据估计，到2020年，重型颅脑损伤将成为全球第三大最常见的死亡和残疾原因。据估计，美国每年有150万人患有创伤性脑损伤，导致230,000多人住院，50,000人死亡。据估计，每年为照顾头部受伤病人而给社会造成的经济成本超过250亿美元。特别是，迫切需要有治疗剂来治疗在参加战斗的美军中大量发生的头部损伤。然而，目前还没有真正有效和被批准的治疗方法可用于治疗脑损伤。谷氨酸受体介导的细胞损伤是颅脑损伤后继发性脑损伤的重要机制。NAAG多肽酶(GCPII和III)是一种胞外酶，在N-乙酰天冬氨酸(NAAG)释放到突触间隙后，将其水解成N-乙酰天冬氨酸(NAA)和谷氨酸(Glu)。抑制GCPII和III会增加NAAG水平，从而激活突触前II组mGluRs，抑制包括谷氨酸在内的递质释放。这些作用有可能在临床条件下提供神经保护，在这种情况下，Glu介导，mGluR3激活减少临床病理。到目前为止，我们的研究小组经过广泛的构效关系研究，已经确定了包括ZJ43、ZJ11和ZJ17在内的许多基于尿素的化合物是具有NM活性的NAAG肽酶抑制剂。来自动物研究的数据表明，给药ZJ 43代表了一种潜在的新策略，可以提供脑外伤后的神经保护。然而，存在一个重要的担忧，即这些化合物的极性太高，不容易穿透血脑屏障(BBB)。前体药物的开发将提供精确的剂量传递到大脑的手段，以及使用较低的剂量范围，从而消除不想要的全身副作用的问题。本研究项目的长期目标是开发这些NAAG肽酶抑制剂作为治疗脑外伤的新疗法。为了加速这些化合物的开发和应用于人体临床试验，本研究计划的近期目标是开发新的前药，以提高我们候选的NAAG肽酶抑制剂的血脑屏障穿透能力。值得注意的是，我们最近的初步数据表明，在Fmr1基因敲除的脆性X综合征和自闭症小鼠模型中，ZJ 43的一种单酯前体药物的活性是母药ZJ 43的三倍。所有这些初步发现鼓励我们继续对我们的NAAG肽酶抑制剂前体药物的设计、合成和药理学研究进行广泛研究。通过这笔为期两年的SBIR赠款的资助，我们打算将我们在脑损伤动物模型中发现的NAAG肽酶抑制剂的有效性提升到更高水平的临床前开发，并最终促进将这一概念转化为临床试验。具体目标1：化合物的合成：合理设计和合成新的前体药物形式的NAAG肽酶抑制剂。根据我们的先导NAAG肽酶抑制剂的结构和一些商业前药的成功结果，将合成目前最佳候选药物ZJ 43、ZJ 11和ZJ 17的10种前药，包括7种单酯或酰胺类前药和3种1，4-二氢吡啶前药，用于目标2中的试验。此外，上述3种母体NAAG肽酶抑制剂将分别制备1.0克作为参考化合物，用于其前药研究，以进行疗效比较。具体目标2：上述前药的药理学研究：使用活体脑损伤模型对上述化合物进行测试。AIM 1中确定的前体药物将在具有良好特征和临床相关的脑损伤大鼠模型中进行细胞保护测试。来自AIM 1的10种前药中的每一种都将以剂量依赖的设计进行评估，在TBI后系统地给药。减少神经细胞死亡的药物疗效将在TBI后24小时使用组织荧光和先进的体视学细胞计数技术进行评估。三种最有效的减少急性细胞死亡的前药将被放大并接受进一步的体内功能测试，以确定它们在减少与脑外伤相关的运动和认知行为障碍方面的有效性。 关键词：NAAG肽酶抑制剂，创伤性脑损伤，脑损伤，治疗，NAAG，GCP II，GCP III，谷氨酸，神经递质，谷氨酸能过度传递，mGluRs，mGluR3，前体药物，单酯，单胺，1，4-二氢吡啶，药物释放系统，血脑屏障，脑损伤模型，中枢神经系统障碍，神经保护。创伤性脑损伤是一个严重的公共卫生问题，估计已成为全球第三大常见的死亡和残疾原因。我们的建议包括新的NAAG肽酶抑制剂及其前药的化学设计和合成，以及这些化合物的体内脑损伤药理研究，这些化合物具有巨大的潜力被开发为治疗创伤性脑损伤的药物。

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) is a serious public health concern. It is estimated that severe TBI will become the third most common cause of death and disability globally by the year 2020. An estimated 1.5 million persons sustain a TBI in the United States annually resulting in more than 230,000 hospitalizations and 50,000 deaths. The annual economic cost to society for the care of head-injured patients has been estimated to exceed $25 billion. In particular, there is a desperate need to have therapeutic agents available to treat head injuries that occur in large numbers among US troops engaged in combat. However, no truly efficacious and approved therapies are currently available for the treatment of TBI. Glutamate-receptor-mediated cell injury acts as an important mechanism of secondary brain damage after TBI. NAAG peptidases (GCPII and III) are extracellular enzymes that hydrolyze N-acetylaspartylglutamate (NAAG) to N-acetylaspartate (NAA) and glutamate (Glu) following the release of the peptide into the synaptic space. Inhibition of GCPII and III increases NAAG levels with the consequent activation of presynaptic group II mGluRs and inhibition of transmitter release including glutamate. These actions have the potential to provide neuroprotection in clinical conditions in which Glu mediates and mGluR3 activation reduces clinical pathology. To date, our research team has identified a number of urea-based compounds including ZJ 43, ZJ 11 and ZJ 17 as NAAG peptidase inhibitors with nM potency after extensive structure activity relationship studies. Data from animal studies have demonstrated that administration of ZJ 43 represents a potential novel strategy to provide neuroprotection after TBI. However, there exists an important concern that these compounds are too polar to readily penetrate the blood-brain barrier (BBB). The development of prodrugs will provide the means for precise dose delivery to the brain as well as the use of lower dose ranges that obviate the problem of unwanted systemic side effects. The long-term goal of this research project is to develop these NAAG peptidase inhibitors as novel therapeutics for TBI. In order to accelerate the development and application of these compounds for human clinical trials, the immediate goal of this research proposal is to develop novel prodrugs to improve the BBB penetration capabilities of our candidate NAAG peptidase inhibitors. It is noteworthy that our very recent preliminary data have demonstrated that one mono-ester prodrug of ZJ 43 is three-fold more active than the parent drug ZJ 43 in Fmr1 knockout mouse models of fragile X syndrome and autism. All these preliminary findings encouraged us to pursue extensive studies on the design, synthesis and pharmacological investigation of prodrugs of our NAAG peptidase inhibitors. Through funding from this two- year SBIR grant, we intend to bring our discovery of the efficacy of NAAG peptidase inhibitors in animal models of TBI to a higher level of preclinical development and ultimately to foster the translation of this concept into clinical trials. Specific Aim 1: Synthesis of compounds: Rational design and synthesis of new prodrug forms of lead NAAG peptidase inhibitors. Based upon the structures of our lead NAAG peptidase inhibitors and the successful results achieved for some commercial prodrugs, ten prodrugs including seven mono-ester or amide prodrugs and three 1,4-dihydropyridine prodrugs of the current best drug candidates ZJ 43, ZJ 11, and ZJ 17 will be synthesized for the testing described in Aim 2. In addition, 1.0 gram each of the above three parent NAAG peptidase inhibitors will be prepared as reference compounds for the studies of their prodrugs for the purpose of efficacy comparison. Specific Aim 2: Pharmacological studies of the above prodrugs: Testing of above compounds using an in vivo TBI model. The prodrugs identified in Aim 1 will be tested for cellular protection in a well- characterized and clinically relevant rat model of TBI. Each of the ten prodrugs from Aim 1 will be evaluated in a dose-dependent design in which drugs are administered systemically after TBI. Drug efficacy for reducing neuronal cell death will be evaluated at 24 hours after TBI using histofluorescence with advanced stereological cell counting techniques. The three most efficacious prodrugs for reducing acute cell death will be scaled up and undergo further in vivo functional testing to determine their efficacy for reducing motor and cognitive behavioral deficits associated with TBI. Key words: NAAG peptidase inhibitors, Traumatic brain injury, Head injury, Therapeutics, NAAG, GCP II, GCP III, Glutamate, Neurotransmitters, Excessive glutamatergic transmission, mGluRs, mGluR3, Prodrug, Mono-ester, Mono-amide, 1,4-Dihydropyridine, Drug delivery system, Blood-brain barrier, TBI model, CNS disorders, Neuroprotection.Traumatic brain injury (TBI) is a serious public health concern, and estimated to become the third most common cause of death and disability globally. Our proposal entails the chemical design and synthesis of novel NAAG peptidase inhibitors and their prodrugs, as well as in vivo TBI pharmacological studies of these compounds, which have the great potential to be developed as therapeutics for the treatment of traumatic brain injury.